The present invention relates to a method for producing a pressure tank for holding a pressurized fluid.
The invention also relates to a pressure tank for holding a pressurized fluid, as well as to a pressure tank group.
Pressure tanks are employed in, e.g., motor vehicles as a means for storing gaseous fuels such as natural gas or hydrogen. Due to the high pressure, the pressure tank must be able to withstand considerable forces. In the case of metallic pressure tanks (e.g., tanks of the class CNG-1 meeting the standard ISO 11439), this can only be achieved by making the walls thereof sufficiently thick, whereby the weight of such tanks is relatively high.
A more favorable relationship between strength and weight can be achieved by utilizing pressure tanks having a reinforcing fiber that is impregnated with a resin wrapped around them. In the case of tanks of classes CNG-2 and CNG-3, metallic hollow bodies (which are also referred to as liners) are coated with a winding consisting of a continuous fiber, whereby here, both the liner and the fiber winding contribute to the ability of the pressure tank to withstand the forces applied thereto. In the case of tanks of class CNG-4, it is the fiber winding alone that is responsible for the strength of the assembly so that a non-load-bearing liner can be used, and, in particular, one consisting of a synthetic material.
The process of wrapping hollow bodies with a continuous fiber for producing pressure tanks in accordance with the state of the art is a relatively laborious process and, in addition, there are certain restrictions associated therewith. As a general rule, the pressure tanks have a cylindrical shape with substantially hemispherical axial end regions, whereby the possible fiber orientations are heavily restricted due to this geometry. In particular, the wrap angle is restricted since the fibers within the end regions of the tank can easily slip. These restrictions are even more significant in the case of freely configurable pressure tanks that deviate from a cylindrical shape with hemispherical end regions so that tighter radii or edges arise. In order to achieve satisfactory force-withstanding properties from the fiber wrapping process, complex multi-axial plies have to be deployed.
The present invention provides a simplified and more advantageous method for producing a pressure tank for holding a pressurized fluid.
The invention also provides a pressure tank for holding a pressurized fluid which is of high strength and which can be produced at relatively low costs, as well as a pressure tank group comprising a plurality of such pressure tanks.